1. Field of the Invention
The present invention relates to a method for determining the concentrations of one or more components in an electrolytic solution, especially in a copper electrochemical deposition solution.
2. Description of the Related Art
In electrochemical deposition (ECD) process, the rigorous control of the relative proportions of respective inorganic and organic ingredients in the ECD bath is critical to the achievement of satisfactory results in the rate of metal film formation and the quality of the film so formed. During the use of the plating bath solution, the plating process may be affected by depletion of inorganic components and organic additives as well as by organic byproduct formation. The ECD bath chemistry therefore must be maintained by periodic replacement of a part or the entire ECD bath. It is therefore important to continuously or periodically monitor the concentrations of inorganic and/or organic components in the ECD bath, and responsively add respective components to the bath to maintain the composition of the bath in an effective state for the electrochemical deposition operation.
In electrochemical-based analysis of organic additive concentration in the ECD bath, the surface state of the working/counter/reference electrode changes with long term operation, due to contamination, corrosion, or re-crystallization of the electrode surface material, which causes drift in the measurement results. Corresponding recalibration or adjustment of the concentration analysis results therefore is required, which is time-consuming and complicated for onsite operation.
It is therefore an object of the present invention to provide a new method for one-point recalibration or adjustment of the concentration analysis results, to reimburse the drift in the measurement results based on one point testing and to provide a modified concentration analysis model with build-in drift reimbursement features.
Other objects and advantages will be more fully apparent from the ensuring disclosure and appended claims.